1. Field of the Invention
This invention relates to a cornea thickness measuring ultrasonic probe for measuring the thickness of the cornea and the distribution thereof by an ultrasonic wave.
2. Related Background Art
Measurement of the thickness of the cornea has been utilized as the monitor of corneal function, and recently it has been used in operations called radial keratotomy, i.e., operations for making myopia into emmetropia by mitigating the curvature of the cornea. In such operations, there is a possibility of injuring the inside spin of the cornea radially and therefore, it is important to adjust the length of the edge of a scalpel and accurately measure the thickness of cornea and the distribution thereof.
The method of measuring the thickness of the cornea may be divided broadly into an optical method and a method using an ultrasonic wave. The optical method can accomplish a generally accurate measurement, but the operation thereof is cumbersome and requires corrections. On the other hand, the method using an ultrasonic wave is simple to handle and can obtain accurate measurement data suitable for use and therefore, is becoming popular.
The probe of an ultrasonic apparatus popular for measurement of an eye includes a single vibrator having a diameter of about 1 mm. To find the distribution of the thickness of the cornea, this probe is moved on the cornea, thereby accomplishing measurement.
This leads to the disadvantages that identification of the measuring position becomes inaccurate and that the tip end of the probe contacting the cornea is small as compared with the diameter of the cornea. Therefore, an unexpected force is exerted on the probe during the movement thereof or during the measurement, which may result in the danger of injuring the cornea. There is also the disadvantage that the thicknesses of the cornea at various positions thereof cannot be properly and stably measured due to the movement of the eyeball including the cornea.